Indirectly-heated cathode heater structure for a cathode ray tube

Abstract

This invention relates to an indirectly-heated cathode heater structure comprising a heat generation section disposed inwardly of an upper portion of a sleeve for generating heat to emit thermions at an electron gun of a cathode ray tube, the heat generation section having a given calorific value being formed to have a length 25˜33 % of the length of the sleeve, whereby heat loss at a lower portion of the sleeve during heating operation of the heater may be minimized, resulting in improving an overshoot rate of the heater.

What is claimed is; 
     
       1. An indirectly-heated cathode heater structure for a cathode ray tube, comprising: a cathode sleeve having an overall length;   a heat generation section disposed inwardly of an upper portion of said cathode sleeve for generating heat to emit thermions from thermion emission material positioned proximate a top end of said cathode sleeve, said heat generation section formed to have a length 25˜33% of said overall length of said cathode sleeve;   a power input section provided at a lower portion of said heat generation section to supply electric power to said heat generation section; and   a wound calorific wire having a number of turns positioned in said heat generation section and said power input section, such that a distance between each turn of said wound calorific wire in said heat generation section is shorter than a distance between each turn of said wound calorific wire in said power input section.   
     
     
       2. An indirectly-heated cathode heater structure for a cathode ray tube as claimed in claim 1, wherein said heat generation section comprises: three twisted portions.   
     
     
       3. An indirectly-heated cathode heater structure for a cathode ray tube as claimed in claim 1, wherein said heat generation section comprises: two twisted portions.